Antennas operate to control energy wave propagation. They are critical components for various wireless transmission and reception systems, for example, telecommunication, aerospace, and/or data transmission systems in general.
Edwin Turner is credited with first generally investigating the spiral antenna in 1954 when he wound a long wire dipole into a spiral form and connected its terminals to a two-wire feed line. Results from his experiments have spurred investigation that continues even today.
Spiral antennas have been designed in various planar or conical shapes, the most common being the equiangular and Archimedean. Spirals operate in three simultaneous fashions: as fast-wave, as leaky-wave, and as traveling-wave antennas. Excited currents in the antenna conductors form a traveling wave that allows for broadband performance. The wave has a phase velocity in excess of the speed of light because of the mutual coupling between neighboring arms. The antenna leaks energy while propagating on the line to produce radiation.